The throttle position sensor (TPS) is typically located on or near the throttle body or throttle shaft. This is a variable potentiometer responsible for sending a variable voltage output to the vehicle's on-board computer to regulate fuel delivery. A malfunctioning TPS can cause the engine to idle inconsistently. The unit is non-adjustable, so a malfunctioning sensor must be replaced. You can check the operation of the TPS with a voltmeter.
Raise the vehicle's hood and prop it open. Locate the throttle position sensor near the throttle body.
Probe the TPS electrical terminal by inserting a straight pin, T-pin or meter probe into the electrical connection marked "SIG" until it contacts the internal wire. Repeat this procedure on the terminal marked "GND." Do not allow the pins to touch.
Turn the ignition to the "Accessories" position but do not crank the engine. Place the positive (red) probe of a voltmeter onto the pin marked "SIG" and the negative (black) probe to the pin marked "GND." The voltmeter should read 0.50- to 1.0-volt with the throttle closed.
Instruct an assistant to depress the accelerator pedal while you take another reading. There should be an increase in the voltage to between 4.0 and 5.0 volts. If the voltage remains at zero, most likely the sensor is malfunctioning.
Disconnect the electrical connector from the TPS.
Remove the mounting screws with a screwdriver then lift the TPS off of the throttle body.
Install the O-ring supplied with the replacement TPS then mount the TPS onto the throttle body. Replace the screws and tighten them with the screwdriver.